Solubility Of Co2 In Sodium Silicate Melts

In this study, CO2, is equilibrated with molten sodium metasilicate (Na2SiO3). Dissolved CO, is analyzed with postexposure carbon analyses and evolved gas analysis (EGA). We interpret these data together with literature data on similar systems. All systems show retrograde solubility, that is, higher solubility at lower temperatures. The evolved gas analysis suggests two forms of CO2 solubility: dissolved CO2 as a molecule to a limited extent and primarily CO2 bound as a compound, likely as Na2CO3. A comparison of heats of solution for this and other systems also suggests compound formation due to the larger heats of solution. The activities of Na2O and Na2CO3 are calculated for this Na2O-CO2-SiO2 system and extended to some sodium aluminosilicate melts as well. Such calculations allow determination of the miscibility limit for Na2CO3 in Na2SiO3 and factors which influence it.